The code was enforcing this option even if a configuration was passed as a parameter to the constructor. If there is something wrong with a configuration and we are passing it to the constructor, we should know if at least the 'baseurlpath' is correct, and if not, fix it somehow.

This bug was producing a default configuration without 'baseurlpath', when no configuration was passed. In that situation, only the default path (/simplesaml) was working correctly.

Add a couple new exceptions, both to signal configuration issues. One can be used to signal an error in a certain configuration, leaving to the user deciding whether it was critical or not, and what to do to deal with it. The other one indicates a configuration exception that we cannot recover from (i.e. missing files), and bootstraps a minimal configuration skeleton that we can use to go on momentarily.